The present invention relates to multi-layered filter media and more particularly to a unique and novel apparatus and method of improving the capacity of particulate removal of a multi-layered filter media.
It has been long known in the filtration art to separate particulate material from a particulate-laden fluid stream by passing such fluid stream at a given face velocity through a variable density sheet of filter medium of a preselected face area with the density of the filter medium increasing from the upstream face of the filter medium toward the downstream face of the filter medium. Or, in other words, the porosity of the filter medium has been greater adjacent the upstream face of the medium so as to capture the larger size particulate materials from a fluid stream to be treated and to then capture the smaller size particulate materials adjacent the downstream face of the filter medium. The prior art also has recognized that such a filtration function can be accomplished with the utilization of successively or immediately layered sheets of filter medium, the resulting filter media being of preselected increasing density and of finer or smaller porosity from upstream to downstream face of the layered facing sheets of filter medium.
In this regard, attention is directed to U.S. Pat. No. 5,082,476, issued to B. E. Kalbaugh et al on Jan. 21, 1992, and U.S. Pat. No. 5,275,743, issued to J. D. Miller et al, both of which patents teach more recent arrangements of immediate filter medium layering. Attentions further directed to U.S. Pat. No. 4,661,255 issued to G. Aumann et al on Apr. 28, 1987, and to U.S. Pat. No. 4,732,675, issued to A. Badolato et al on Mar. 22, 1988, both of which patents teach multi-layered filter medium of varying density but which also fail to recognize the inventive features set forth herein, let alone provide a unique apparatus and method to accomplish the novel arrangement herein described.
Finally, attention is directed to several bullets of interest relating to pore size characteristics: namely, ASTM, Designation F3 16-86, published April 1986 and entitled, "PORE SIZE CHARACTERISTICS OF MEMBRANE FILTERS BY BUBBLE POINT AND MEAN FLOW PORE TEST;" "Advances in Filtration and Separation Technology," Vol. 8, AFS Society pp. 97-99 (1994), entitled, "AIR PERMEABILITY AND PORE DISTRIBUTION OF A DUAL-LAYERED MICROGLASS FILTER MEDIUM," by Kyung-Ju Choi; Fluid Particle Separation Journal, Vol. 7, No. 1, March 1994 entitled, "PORE DISTRIBUTION AND PERMEABILITY OF CELLULOSIC FILTRATION MEDIA," by Kyung-Ju Choi; TAPPI 1995 Non-woven Conference, pp. 44-50, entitled, "PERMEABILITY PORE SIZE RELATIONSHIP OF NON-WOVEN FILTER MEDIA," by Kyung-Ju Choi; INJ., Vol. 6, No. 3, pp. 62-63, entitled, "PREDICTION OF AIR PERMEABILITY AND PORE DISTRIBUTION OF MULTI-LAYERED NON-WOVENS," by Kyung-Ju Choi; and, FLUID PARTICLE SEPARATION JOURNAL, Vol. 9, No. 2, June 1996, pp. 136-146, entitled, "FLUID FLOW THROUGH FILTER MEDIA AT A GIVEN DIFFERENTIAL PRESSURE ACROSS MEDIA," by Kyung-Ju Choi.
The present invention, recognizing the filtration capacity limitations of past filtering arrangements, as well as the reasons therefore, provides a unique and novel filter arrangement involving a structure and method for spacing successive medium layers which maximizes filtration capacity in a straightforward and economical manner and which requires a minimum of additional parts and operating steps to accomplish the same.
Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein.